The elevator is a type of vertical transport equipment that efficiently moves people or goods between floors (levels, decks) of a building, vessel or other structures. Automatic elevator car systems, i.e., systems in which the car door automatically opens when the car reaches a floor and close before the car leaves a floor, are well-known in the art. Elevator car landing doors protect passengers and unauthorized persons from falling into the elevator shaft.
Elevator systems further include a set of landing doors which are kept locked on each floor to prevent unauthorized person access into the elevator shaft at all time, and protect them from falling into the shaft. In automatic elevator car systems, the landing door may be automatically opened and closed or may be manually opened and closed. The door is unlocked and opened by a machine preferably sitting on the roof of the car, which also drives the doors that travel with the car. Door controls are provided to close immediately or reopen the doors. A control means is provided for moving the car from one of the floors to another, stopping the car at a floor, causing opening and closing the elevator doors at a floor at which the car is stopped.
Elevator systems usually includes a switch or switches operable when the landing door is closed and a switch or switches operable when the car door or gate is closed which permits the car hoisting apparatus to move the car to another floor when all switches have been operated in closed state. Also, such systems usually include a mechanical locking device which prevent opening of the doors unless the car is substantially level with the floor at which the doors control entrance and egress from the car. The plurality of switches on the car and at the floors which are connected to the control means, when all the doors are closed and locked, permit operation of the circuits in the control means which cause the car to move. Usually included in such plurality of switches are, a switch at each floor controlled in accordance with the position of the car door and operated by the locking mechanisms which hold the doors closed until the locking mechanisms are automatically released when the car is at a floor.
Elevators incorporate several safety features to ensure safe operation of the elevator. However, elevators from time to time, require service and maintenance. When elevator mechanics are conducting inspection and maintenance of the elevators, it is often necessary to use a short stub to short circuit/bypass a certain section of the elevator safety circuit to facilitate installation, debugging, or detection of problems. Using a jumper which is a short length of conductor used to bypass a section of elevator safety circuit. Some switches can be bypassed, so that the elevator can operate without the protection of some switches. Leaving the bypass in place after its use may result in failure of the equipment to operate properly and accidents, for example, the elevator can move while the doors are open, when the relevant circuits are left bypassed.
WO2011/090665 discloses an elevator tool and method for safely short circuiting an elevator switch. The elevator safety tool includes a control module that receives elevator operating status data and determines whether an elevator operating status is normal or service. A relay includes a switch that is movable from a close to an open position when the elevator operating status changes from service to normal. The tool may also include a pair of pen heads connected to the relay by short stubs. The method includes receiving data, determine elevator operating status based on the data, closing a switch to allow conduction between two pen heads when the elevator operating status is determined to be service, and opening the switch when the elevator operating status is determine by normal.
U.S. Pat. No. 5,443,142 discloses, An automatic elevator system having car movement controls, door controls, a door operating mechanism for automatically opening and closing at least the car door and first switch contacts operable when the car and hoistway doors are closed to permit the car to move from a floor in combination with further switch contacts which are operable in accordance with the positions of the doors and which prevent the car from moving from a floor when the first switch contacts are operated before the further switch contacts to prevent movement of the car from a floor when the first switch contacts have been operated or shunted by unauthorized persons or by a short circuit and other means to protect against failures of other circuits operated by the first switch means and further switch means.
One object of the present invention is to provide a simple system for safely bypass an elevator safety circuit by switching the elevator into inspection mode of operation with relatively simple changes in a conventional automatic elevator system and protect the elevator against bypass of elevator safety devices.